[Discussion on the concept problem of the specific retention volume in gas chromatography]

The concept problem in the definition of well-known specific retention volume in GC is proposed in this paper. The specific retention volume Vg is usually defined as the net retention volume per gram of liquid phase corrected to 273.15 K in some literatures, and is widely appeared in journals and textbooks as one of the most important absolute retention value in GC, though it is less practical than the relative retention value in the qualitative analysis. Being inspired in the discussion of pressure correction in GC, the author thinks that the temperature correction term in the Vg definition is neither correct nor necessary. The problem was originated from the misunderstanding of the pressure correction of the adjusted retention volume. It is emphasized here that the net retention volume obtained by correction of the adjusted retention volume by compressibility factor j is the retention parameter in term of the column geometrical volume rather than a gas volume. The net retention volume per gram of liquid phase is an absolute retention parameter sufficient to measure the retention power. The author thinks that it is necessary to discuss and clarify the problem to avoid any possible errors being introduced in some cases, such as in the estimation of some thermodynamic parameters.